As a soldering apparatus that achieves solder bonding without using a flux, there is an apparatus in which oxides on a metal surface of a bonding target member are reduced with a reducing agent such as formic acid before solder bonding is achieved. As means for vaporizing a formic acid liquid (vaporization target liquid) in order to supply formic acid gas to a bonding target member, there is means in which, when a carrier gas such as nitrogen is introduced into a bubbling tank in which a formic acid liquid is reserved, the carrier gas, supplied into the formic acid liquid in the bubbling tank, ascends toward a space above the liquid surface of the formic acid liquid and, at this time, a formic acid gas is generated since the formic acid liquid is turned to gas and mixed into the carrier gas (for example, see Patent Document 1).